hermes-agent/tests/agent/test_empty_tool_name_loop_dampening.py
Teknium 348e9912ff
fix(agent): execute valid tool calls in mixed batches with invalid names (#66317)
Degrading models (observed with gpt-5.6 past ~350K input) emit tool-call
batches like 6 valid named calls + 1 blank-name call. Previously the
whole turn was voided — every valid call got 'Skipped: another tool call
in this turn used an invalid name' — and three such batches tripped the
3-strike stop, killing sessions that were still making progress.

Now a mixed batch error-results ONLY the invalid call(s) (terse
anti-priming error for blank names per #47967, catalog dump for typos)
and dispatches the valid subset for execution. The assistant message
keeps every emitted call so provider-side tool_call/result pairing stays
intact. The 3-strike counter only advances when a turn contains NO valid
call, so a fully-degenerate model still stops while a mostly-coherent
one keeps working. Broken JSON args on a never-executing invalid call no
longer trigger the whole-turn JSON retry loop.

Field evidence: July 2026 debug bundle showed gpt-5.6-sol emitting
6-call batches with one blank-name rider at 559K/384K-token context in
two separate sessions; 13 valid tool calls were discarded before the
session stopped as partial.
2026-07-17 06:48:42 -07:00

293 lines
12 KiB
Python

"""Regression for #47967 — empty-name phantom tool calls.
Weak open models (mimo, nemotron-class) that see tool-call XML/JSON sitting in
file contents or tool output get *primed* and emit their own structured tool
calls that mimic the payload — usually with an empty/whitespace ``name``. Those
calls can't be fuzzy-repaired toward a real tool, so the dispatch loop returns an
error and the model retries. Before this fix, every empty-name error dumped the
full tool catalog back to the model, which fed the priming loop more names to
mimic and inflated context 3-4x across the retry budget.
The fix: a blank/whitespace-only tool name gets a terse anti-priming error that
tells the model in-context tool-call syntax is DATA, with NO catalog dump. A
genuinely-wrong-but-nonempty name (an actual typo) still gets the full catalog
so the model can self-correct.
These assert the *behavior contract* of the dispatch branch (what content goes
back to the model for each name shape), exercised end-to-end through
``AIAgent.run_conversation`` against an in-process mock provider — not a snapshot
of the message string.
"""
from __future__ import annotations
import json
import os
import shutil
import sys
import tempfile
import threading
from http.server import BaseHTTPRequestHandler, HTTPServer
import pytest
# Repo root = three levels up from tests/agent/<file>.
_REPO_ROOT = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
if _REPO_ROOT not in sys.path:
sys.path.insert(0, _REPO_ROOT)
class _MockHandler(BaseHTTPRequestHandler):
# Set by the fixture before each request cycle.
captured_requests: list = []
response_queue: list = []
def do_POST(self): # noqa: N802 (http.server API)
length = int(self.headers.get("Content-Length", 0))
req = json.loads(self.rfile.read(length).decode())
type(self).captured_requests.append(req)
is_stream = req.get("stream") is True
if type(self).response_queue:
resp = type(self).response_queue.pop(0)
else:
resp = _text_resp("DONE")
msg = resp["choices"][0]["message"]
if is_stream:
content = msg.get("content") or ""
tcs = msg.get("tool_calls")
self.send_response(200)
self.send_header("Content-Type", "text/event-stream")
self.end_headers()
chunks = [{"id": "m", "choices": [{"index": 0, "delta": {"role": "assistant", "content": ""}, "finish_reason": None}]}]
if content:
chunks.append({"id": "m", "choices": [{"index": 0, "delta": {"content": content}, "finish_reason": None}]})
if tcs:
for ti, tc in enumerate(tcs):
chunks.append({"id": "m", "choices": [{"index": 0, "delta": {"tool_calls": [{
"index": ti, "id": tc["id"], "type": "function",
"function": {"name": tc["function"]["name"], "arguments": tc["function"]["arguments"]}}]}, "finish_reason": None}]})
chunks.append({"id": "m", "choices": [{"index": 0, "delta": {}, "finish_reason": "tool_calls" if tcs else "stop"}]})
for c in chunks:
self.wfile.write(f"data: {json.dumps(c)}\n\n".encode())
self.wfile.write(b"data: [DONE]\n\n")
self.wfile.flush()
else:
body = json.dumps(resp).encode()
self.send_response(200)
self.send_header("Content-Type", "application/json")
self.send_header("Content-Length", str(len(body)))
self.end_headers()
self.wfile.write(body)
def log_message(self, *a, **kw): # silence the default stderr logging
pass
def _tc_resp(name: str, args: str = "{}") -> dict:
return {
"id": "m",
"choices": [{"index": 0, "message": {
"role": "assistant", "content": "",
"tool_calls": [{"id": "call_1", "type": "function",
"function": {"name": name, "arguments": args}}]},
"finish_reason": "tool_calls"}],
"usage": {"prompt_tokens": 10, "completion_tokens": 0, "total_tokens": 10},
}
def _batch_tc_resp(calls: list[tuple[str, str]]) -> dict:
"""Multi-call batch response: calls = [(name, arguments), ...]."""
return {
"id": "m",
"choices": [{"index": 0, "message": {
"role": "assistant", "content": "",
"tool_calls": [
{"id": f"call_{i}", "type": "function",
"function": {"name": name, "arguments": args}}
for i, (name, args) in enumerate(calls)
]},
"finish_reason": "tool_calls"}],
"usage": {"prompt_tokens": 10, "completion_tokens": 0, "total_tokens": 10},
}
def _text_resp(text: str) -> dict:
return {
"id": "m",
"choices": [{"index": 0, "message": {"role": "assistant", "content": text}, "finish_reason": "stop"}],
"usage": {"prompt_tokens": 10, "completion_tokens": 0, "total_tokens": 10},
}
@pytest.fixture()
def agent_env():
"""Spin up the mock provider + an isolated HERMES_HOME, yield (agent, helpers)."""
_MockHandler.captured_requests = []
_MockHandler.response_queue = []
srv = HTTPServer(("127.0.0.1", 0), _MockHandler)
port = srv.server_address[1]
t = threading.Thread(target=srv.serve_forever, daemon=True)
t.start()
test_home = tempfile.mkdtemp(prefix="hermes_e2e_47967_")
os.makedirs(os.path.join(test_home, ".hermes"))
prev_home = os.environ.get("HERMES_HOME")
os.environ["HERMES_HOME"] = os.path.join(test_home, ".hermes")
# Import fresh so the patched conversation_loop is exercised even when the
# module was imported earlier in the same worker.
for mod in list(sys.modules):
if mod == "run_agent" or mod.startswith("agent.") or mod.startswith("tools.") or mod.startswith("hermes_"):
del sys.modules[mod]
from run_agent import AIAgent
agent = AIAgent(
api_key="test-key", base_url=f"http://127.0.0.1:{port}/v1",
provider="openai-compat", model="test-model",
max_iterations=10, enabled_toolsets=[],
quiet_mode=True, skip_context_files=True, skip_memory=True,
save_trajectories=False, platform="cli",
)
agent.valid_tool_names = {"terminal", "read_file", "write_file", "execute_code", "session_search"}
try:
yield agent, _MockHandler
finally:
srv.shutdown()
shutil.rmtree(test_home, ignore_errors=True)
if prev_home is None:
os.environ.pop("HERMES_HOME", None)
else:
os.environ["HERMES_HOME"] = prev_home
def _tool_results(handler) -> list[str]:
out = []
for req in handler.captured_requests:
for m in req.get("messages", []):
if m.get("role") == "tool":
out.append(m.get("content", ""))
return out
@pytest.mark.parametrize("blank", ["", " ", "\n", "\t "])
def test_empty_tool_name_gets_terse_error_no_catalog(agent_env, blank):
"""A blank/whitespace tool name must NOT trigger a full tool-catalog dump."""
agent, handler = agent_env
handler.response_queue.append(_tc_resp(blank, "{}"))
handler.response_queue.append(_text_resp("Recovered in plain text."))
agent.run_conversation("read ./payload and report", conversation_history=[], task_id="t")
joined = " ".join(_tool_results(handler))
assert "tool name was empty" in joined
# The whole point: do not feed the priming loop the catalog of names.
assert "Available tools:" not in joined
def test_unknown_nonempty_name_keeps_catalog(agent_env):
"""A genuinely-wrong NONempty name still gets the catalog for self-correction."""
agent, handler = agent_env
handler.response_queue.append(_tc_resp("frobnicate_xyz", "{}"))
handler.response_queue.append(_text_resp("ok plain text"))
agent.run_conversation("do a thing", conversation_history=[], task_id="t")
joined = " ".join(_tool_results(handler))
assert "frobnicate_xyz" in joined
assert "Available tools:" in joined
assert "tool name was empty" not in joined
# ── Mixed batches: valid calls execute, invalid calls get error results ──
#
# Degrading models (observed with gpt-5.6 past ~350K input; jonny's July 2026
# report) emit batches like 6 named calls + 1 blank-name call. Before the fix,
# the whole turn was voided ("Skipped: another tool call in this turn used an
# invalid name") and three such batches halted the session as partial even
# though most of the model's work was coherent.
def test_mixed_batch_executes_valid_and_errors_blank(agent_env):
"""Valid siblings of a blank-name call must execute, not be skipped."""
agent, handler = agent_env
agent.valid_tool_names = agent.valid_tool_names | {"todo"}
handler.response_queue.append(_batch_tc_resp([("todo", "{}"), ("", "{}")]))
handler.response_queue.append(_text_resp("done"))
result = agent.run_conversation("track work", conversation_history=[], task_id="t")
joined = " ".join(_tool_results(handler))
# The blank call got the terse anti-priming error...
assert "tool name was empty" in joined
# ...the valid sibling was NOT punished...
assert "Skipped: another tool call" not in joined
# ...and actually executed (todo returns its list, not an error result).
assert result.get("completed", False)
def test_mixed_batch_preserves_tool_call_result_pairing(agent_env):
"""Every emitted tool_call keeps a matching tool result (provider invariant)."""
agent, handler = agent_env
agent.valid_tool_names = agent.valid_tool_names | {"todo"}
handler.response_queue.append(_batch_tc_resp([("todo", "{}"), ("", "{}")]))
handler.response_queue.append(_text_resp("done"))
result = agent.run_conversation("track work", conversation_history=[], task_id="t")
msgs = result["messages"]
tc_ids = []
for m in msgs:
if isinstance(m, dict) and m.get("role") == "assistant" and m.get("tool_calls"):
tc_ids.extend(tc["id"] for tc in m["tool_calls"])
result_ids = [
m.get("tool_call_id") or "" for m in msgs
if isinstance(m, dict) and m.get("role") == "tool"
]
# Both the valid and blank call must appear in the assistant message,
# and each must have exactly one matching tool result.
assert set(tc_ids) == {"call_0", "call_1"}
assert sorted(result_ids) == sorted(tc_ids)
def test_mixed_batches_do_not_strike_out_session(agent_env):
"""4 consecutive mixed batches must not trip the 3-strike halt."""
agent, handler = agent_env
agent.valid_tool_names = agent.valid_tool_names | {"todo"}
for _ in range(4):
handler.response_queue.append(_batch_tc_resp([("todo", "{}"), ("", "{}")]))
handler.response_queue.append(_text_resp("survived"))
result = agent.run_conversation("keep going", conversation_history=[], task_id="t")
assert result.get("completed", False)
assert not result.get("partial", False)
assert "survived" in (result.get("final_response") or "")
def test_all_invalid_batch_still_strikes_out(agent_env):
"""A turn with NO valid call must still advance the 3-strike halt."""
agent, handler = agent_env
for _ in range(3):
handler.response_queue.append(_batch_tc_resp([("", "{}"), (" ", "{}")]))
result = agent.run_conversation("degenerate", conversation_history=[], task_id="t")
assert result.get("partial", False)
assert "invalid tool call" in (result.get("error") or "")
def test_mixed_batch_invalid_call_with_broken_json_does_not_retry_turn(agent_env):
"""Broken args on a never-executing invalid call must not trigger the JSON retry loop."""
agent, handler = agent_env
agent.valid_tool_names = agent.valid_tool_names | {"todo"}
handler.response_queue.append(_batch_tc_resp([("todo", "{}"), ("", '{"unclosed')]))
handler.response_queue.append(_text_resp("done"))
result = agent.run_conversation("track work", conversation_history=[], task_id="t")
assert result.get("completed", False)
# Exactly 2 chat API calls: the batch turn + the final answer. A JSON
# retry would add a third identical request.
chat_calls = [r for r in handler.captured_requests if "messages" in r]
assert len(chat_calls) == 2